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• downstream end of the ladder to 0.25 foot at the upstream end of the <br />ladder and the ladder flow will be 15 cfs. <br />c. Refer to Table 1 for ladder flows, slot and orifice <br />velocities, and head drop per pool. <br />4. Other Considerations. <br />a. Biological and Technical Considerations. <br />('1) The two target species prefer swii~ning close to <br />the river bottom. At the fishway entrances, fish can remain near the <br />river bottom and swim through the side-opening slide gates. These gates <br />can be adjusted to achieve the desired head drop at the entrance and the <br />gate opening will be flush with the invert elevation of the entrance at <br />4,560.0 feet. <br />(2) The fish ladder is positioned so that fish migrat- <br />ing up the river will be attracted to the discharge from the new sluice <br />gate. These fish would most likely locate the downstream entrance. <br />Fish migrating up the left bank will be stopped by the obstruction of <br />the dam. They should locate the west entrance by swimming across the <br />downstream face of the dam searching for upstream passage. The entrances <br />are also positioned downstream of the existing concrete spillway apron. <br />At low flows, the spillway apron could possibly become a velocity and <br />depth barrier to migrating fish. <br />(3) The interior configuration of the ladder is similar <br />to Alternate No. 1 and should be compatible with the swimming abilities <br />and preferences of the two target species. <br />(4) The ladder structure is located on the inside of a <br />river bend. This location will likely accumulate sediment near the fish- <br />way exit. Therefore, a new sluice gate is included to flush sediment <br />past the exit. <br />b. Impacts. <br />(1) Impacts Affecting RWPC. <br />(a) To attain desirable fish attraction con- <br />ditions, RWPC may be asked to slightly modify their standard operating <br />procedures. During high spring flows, releases of flow through the <br />existing sluice gates should be limited to a minimum amount of flow. The <br />• new sluice gate should release the larger amount of water to create <br />desirable fish attraction conditions. The purpose of the new sluice gate <br />29 <br />